Title Trace element and molecular markers of organic carbon dynamics along a shelf-basin continuum in sediments of the western Arctic Ocean
Author Belicka, L.L.; Macdonald, R.W.; Harvey, H.R.
Author Affil Belicka, L.L., University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, MD. Other: Institute of Ocean Sciences, Canada
Source Marine Chemistry, 115(1-2), p.72-85, . Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0304-4203
Publication Date Jun. 20, 2009
Notes In English. 83 refs. GeoRef Acc. No: 307704
Index Terms carbon isotopes; geochemistry; isotopes; marine deposits; metals; radioactive isotopes; sediments; statistical analysis; microelement content; United States- -Alaska; Arctic Ocean--Beaufort Sea; Alaska; Arctic Ocean; Beaufort Sea; biochemistry; biomarkers; C-13/C-12; carbon; carboxylic acids; concentration; continental shelf; cores; Eh; fatty acids; isotope ratios; lead; lipids; manganese; marine sediments; metabolism; northern Alaska; organic acids; organic carbon; organic compounds; Pb-210; principal components analysis; rhenium; stable isotopes; sulfides; trace elements; trace metals; United States; western Arctic Ocean
Abstract Molecular organic biomarkers together with trace element composition were investigated in sediments east of Barrow Canyon in the western Arctic Ocean to determine sources and recycling of organic carbon in a continuum from the shelf to the basin. Algal biomarkers (polyunsaturated and short-chain saturated fatty acids, 24- methylcholesta-5,24(28)-dien-3beta -ol, dinosterol) highlight the substantial contribution of organic matter from water column and sea-ice primary productivity in shelf environments, while redox markers such as acid volatile sulfide (AVS), Mn, and Re indicate intense metabolism of this material leading to sediment anoxia. Shelf sediments also receive considerable inputs from terrestrial organic carbon, with biomarker composition suggesting the presence of multiple pools of terrestrial organic matter segregated by age/lability or hydrodynamic sorting. Sedimentary metabolism was not as intense in slope sediments as on the shelf; however, sufficient labile organic matter is present to create suboxic and anoxic conditions, at least intermittently, as organic matter is focused towards the slope. Basin sediments also showed evidence for episodic delivery of labile organic carbon inputs despite the strong physical controls of water depth and sea-ice cover. Principal components analysis of the lipid biomarker data was used to estimate fractions of preserved recalcitrant (of terrestrial origin) and labile (of marine origin) organic matter in the sediments, with ranges of 12- 79%, 14-45%, and 37-66% found for the shelf, slope, and basin cores, respectively. On average, the relative preserved terrestrial organic matter in basin sediments was 56%, suggesting exchange of organic carbon between nearshore and basin environments in the western Arctic.
URL http://hdl.handle.net/10.1016/j.marchem.2009.06.007
Publication Type journal article
Record ID 65004755